Twisted conductors and cables



Oct. 11, 1960 J.-c. LILLY 2,956,102

' TWISTED coNnucToRs AND CABLES original Filed uam 12, 1957 27 27 INVENTOR.

j/ @iep/2 C MY ATTORNEYS United States Patent Oiice 2,956,102 Patented Oct. 1l, 1960 TWISTED CONDUCTORS AND CABLES Joseph C. Lilly, Plainfield, Conn., assignor to The Plastic Wire & Cable Corporation, Jewett City, Conn., a corporation of Connecticut Ori inal a lication Mar. 12 1957, Ser. No. 645,599,

iiw Patlt No. 2,869,3`16,dated Jan. 20, 1959. Divided and this application Sept. 11, 1958, Ser. No. 760,395

3 Claims. (Cl. 174-34) This invention relates to electrical wires or conductors and cables made therefrom. More particularly, thepres'- ent invention relates to an improved twisted pair circuit for use as an open wire or assembled into cables for the transmission of intelligible electric signals.

This application is a division `of my copending application Serial No. 645,599, tiled March 12, 1957, now Patent No. 2,869,316, granted January 20, 1959.

Heretofore, in producing cables, it has been the practice to produce twisted pairs which are distinct by reason of the fact that each has twists of predetermined fixed length. In use in cables, neighboring or juxtaposed pairs or subassemblies have different predetermined twist lengths so as to cause the members of one pair to be transposed with respect to those of another pair in order to reduce to a minimum inductive disturbances as, `for example, cross-talk when the cable is used for `telephone purposes. This, therefore, required a predetermined number of different and distinguishable subassemblies, each having a different rate of twist or twist length and that each pair be identified. It also required that the pairs be located in predetermined relation in the c able and their position maintained in the cable. This required the manufacture and storage of a number of diiferent subassemblies and particular care in the selection and assembly of them into a cable, all of which adds to the cost of the cable.

The present invention overcomes these difliculties and disadvantages of the prior constructions by providing a single twisted pair having the lengths of the twists in the pair continuously varying throughout and preferably controlling the variation at random so that there is no fixed pattern in the twist variation whereby lengths of the one twisted pair can be placed adjacent one another in open circuits or in cables with fa minimum of difficulty from inductive disturbances therebetween.

A feature of the present invention resides in the fact that but a single twisted pair need be produced which can be safely utilized in an open circuit or in a cable without the danger of electric disturbances being present between the twisted pairs therein, thus eliminating the necessity of making and storing a large number of different and distinguishable pairs Ior subassemblies.

Another feature of the invention resides in the fact that with the present invention the cable assembly and construction can be simplified.

Other features and advantages of the invention will be apparent from the specification and claims when considered in connection with the drawings in which:

Figure l shows a diagrammatic view of the apparatus for making the twisted pair of the present invention.

Fig. 2 shows two twisted pairs in side-by-side relation as they would appear in a cable.

Fig. 3 shows a speed time chart showing the variation of capstan speed.

Fig. 4 shows one form of speed-changing device.

As shown in the drawings, a pair of wires a and b, preferably insulated electrical conductors, are fed from reels 10, 11 through a conventional twisting device 12 which includes a rotatable yer 13 driven from a motor 14 or other source of power so as to carry the wire a around the wire b as it passes through the guide 15 and form a twist therewith as the wires are drawn therethrough by a capstan 16. The twisted pairs are then fed to a takeup spool 17 which may be driven by a usual constant torque motor 18 or the like means. It will be apparent that the length of cach twist depends upon the rate at which the wire is drawn by the capstan through the twisting device, i.e., the rate of speed of the capstan with respect to the rate of rotation of the flyer, so that by changing gears in the drive to the capstan a twisted pair having the twists of a predetermined length could be produced. The foregoing describes a standard machine now in use for forming twisted pairs having a uniform length lof twist throughout.

In contradistinction to such a twisted pair, the present invention provides a novel twisted pair in which the length of successive twists therein is continuously changing. As shown in the top pair of the cable of Fig. 2, the length of the twist decreases to R, increases to S, decreases to T and then increases while in the lower pair the length of the twist increases to U, decreases to V, increases to X and decreases. It will be noted that the rate of change in length is constantly varying and the reversals thereof occur at random so that when two or more twisted pairs are put in juxtaposition yin a cable the danger of cross-talk or the disturbances in the signal is substantially eliminated.

Since the length of twist in each pair is constantly varying, the present invention greatly simplifies the method and manufacture of novel cables because it is no longer necessary to maintain stocks of twisted pairs each having a predetermined different length of twist and it is no longer necessary to arrange the pairs having dilerent length twists therein in predetermined position in the cable and to maintain them iii said positional arrangement to prevent inductive disturbances in the cable.

While either the speed of the iiyer or capstan can be varied, in the illustrated form of apparatus the capstan, as shown in Fig. l, is driven from the motor 14 through a speed-changing device 19.

Any suitable variable speed drive may be used. One such drive is shown in Fig. 4 wherein the input shaft 20 driven from motor 14 has an expansible pulley 21 thereon and the output shaft 22 has an expansible pulley 23 thereon. A belt 24 connects the pulleys. A pair of pivoted levers 25, 26 'are connected to the sides of the pulleys to move the sides in opposite directions to increase the beltengaging diameter of one pulley and decrease the beltengaging diameter of the other pulley to vary the speed between the shafts 20 and 22. The levers have their ends pivotally connected to nuts 27 threaded on the oppositely threaded portion of a rotatable adjusting sli-aft 28. By controlling the rotation of shaft 28, it will be seen that the relative speed of the capstan and the iiyer can be regulated to control the length of twist.

in order to provide for a constantly varying length of twist in the wires, the present invention controls the rotatable member or shaft 28 of the variable speed drive. While the shaft 23 can be driven from the motor 14 or by a separate variable speed motor having suitable controls thereon, in the illustrated form of apparatus the rotating member 28 is driven from the capstan 16 through a gear reducer 29 so as to rotate the screw within the speed changer or variable speed drive so as to cause the levers 25, 26 to be pivoted about their pivots and move the side of the pulleys toward or away from one another to increase or decrease the effective diameter of the pulleys and change the speed of the capstan. Since the control member 2S is driven with the capstan which is being rotated at a variable speed, the change in speed of the speed-changing device will also be variable so that the change of length of the twist in the pair is continuously varying.

In order to further modify the twist in the pair, the present invention provides a novel control means for c/introlliit,j 'de'rotating'v yadjusting shaftr of theV speed changer. In theherein form of apparatus a reversing mechanism 30 is inserted in the drive for the shaft 28 and a control for the reversing mechanism is providedV to periodically reverse the rotation of the shaft. While this control can take the form of a tape, cam or any other type of programming device capable of effecting random operation of the shaft, it is herein illustrated as comprising a rotatable screw 31 having a nut 32 thereon and driven with the rotating shaft 28. The nut has a switch 33 thereon connected to the control box 34 housing the usual electrical relays and air control means (not shown) for controlling the usual iiuid operated reversing clutch means (not shown) in the reversing mechanism so that by actuating the reversing switch the direction of rotation of the shaft 28 can be reversed.

The control of the switch can be carried out by any suitable programming device such as tape, cams, punch cards, photocells and the like devices capable of producing random reversal of the shaft 28. In the illustrated form of apparatus it comprises a drum 35 having projecting at random from its surface a plurality of actuators 36. The drum is positioned adjacent the screw and is rotated to cause the actuators to be moved into .the path of movement of the reversing switch 33 to engage the sameand operate the reversing means to cause a reversal o'frotation of the shaft 28. The drum can be driven in timed relation with the shaft 28 or by motor 14 but it is herein illustrated as being driven by a separate motor 35d which can be a single speed or variable speed motor as desired. Preferably7 the drum is provided with continuous end projections 37 which form limit controls for actuating the switch and reversing the changing speed at predetermined points to deiine the maximum and minimuml length of twist in the pair.

With this construction it will be seen that the rotation of the shaft 28 is continually varied between limits and reversed at random to cause the variable speed drive to continuously vary at random the speed of the capstan with respect to the iiyer drive and hence the length or" each twist in a twisted pair.

The speed-time chart shown in Fig. 3 is a section of a chart taken on an actual run of a machine forming a twisted pair of the present invention and graphically shows the variation in `the speed of the capstan on a time basis, and, since the speed of the liyer is constant, the chart shows the variation between the speed of the capstan and flyer drives. The notations at the left in Fig. 3 indicatethe speeds representing the maximum and minimum lengths of twist in the pair and the zigzag curve having irregular reversals clearly show the continuous and random nature of the change in relative speeds and resulting increasing and decreasing lengths of twist. The portions of the curve below the minimum length line were produced during the starting and stopping of the machine.

The control means for producing twisted pairs of the present invention can be added to existing machines without substantial' alteration thereto or can be built into the machine ias original equipment.

Although the present machine is intended to produce twisted pairs having constantly -varying 'lengths of twist, it can be adjusted to produce twisted pairs of ixed constant length of twist. This is accomplished by adjusting the capstan speed to the required speed as shown on the tachometer 38 on the output shaft 22 and then locking the adjusting shaft 28 against further adjustment by a suitable clamp 39 actuated by a handwheel 40 on the control panel 41. Also, the clutch in the reversing mechanism can be rendered inoperative, by means of handwheels 42, 43 on the control panel so that the connection will cease to drive the shaft 28 whereupon the capstan will be driven at a constant rate of speed to produce twists of constant length.

Itwill be seen, therefore, that the illustrated machine is very versatile in that it can produce twisted pairs having a fixed length oftwist or a continuously varying length of twist as required.

Variations and modiiications may be made within the scope of the claims and portions of the improvements may be used without others.

' I claim:

1.` An article of manufacture comprising a twisted pair of electrical conductors of indefinite length having the length of the succeeding twists therein continuously increasing and decreasing at random with no iixed pattern of twist variation.

2. A cable comprising a plurality of pairs of twisted electrical conductors of indefinite length, each pair having the twists therein of continuously varying random lengths with no ixed pattern of twist variation whereby the wires in the adjacent pairs are in transposed noninductive relation.

3. A cable comprising a plurality of juxtaposed pairs of twisted electrical conductors of indefinite length, the length of the twists in each pair continuously increasing and decreasing at random with no fixed pattern of twist variation whereby the wires in the adjacent pairs are in non-inductive relation.

Patterson May 16, 1893 Patterson July 25, 1893 

